Purpose: CAR-T cell therapy relies mainly on retroviral/lentiviral vectors, which carry risks of carcinogenicity and complex manufacturing. PiggyBac transposon systems offer a safer, simpler non-viral alternative for stable transgene expression, but primary T lymphocytes are difficult to transfect efficiently. A polymeric nanomicelle carrier was developed to deliver PiggyBac transposon/transposase plasmids to human T cells.
Hypothesis: If a reduction-sensitive cationic nanomicelle based on mPEG-P(Asp-AED-g-HFB) (PAEF) delivers PiggyBac transposon and transposase plasmids to primary human T lymphocytes, then it will condense and protect DNA, mediate efficient transfection with low toxicity, and enable stable CAR transgene expression and functional CAR-T cells.
Aims: Synthesize and characterize reduction-sensitive polymeric nanomicelles. - Evaluate DNA condensation, protection, and triggered release. - Optimize transfection conditions for primary human T cells. - Assess CAR-T transduction efficiency, phenotype, and cytotoxic function after PiggyBac-mediated gene transfer.
Delivery system:
Component: Polymer; Details: mPEG-P(Asp-AED-g-HFB), abbreviated PAEF
Component: Architecture; Details: Block copolymer nanomicelle; PEG corona; reduction-sensitive disulfide interlayer; fluorocarbon core
Component: Payload; Details: PiggyBac transposon plasmid encoding EGFRvIII CAR; super PiggyBac transposase plasmid; RFP reporter
Component: Complexation; Details: Electrostatic binding at various N/P ratios
Component: Optimal N/P; Details: 40
Component: Size / charge; Details: Blank micelles ~62.7 nm; polyplex at N/P 40 ~134.5 nm, zeta ~+20.9 mV
Component: Targeting ligand; Details: None
Component: Key feature; Details: Reduction-sensitive disulfide bonds for intracellular DNA release; PEG shell for stability
Approach: In vitro only. No in vivo animal studies. - Cells: Primary human T cells from healthy donors, activated with anti-CD3/CD28 beads for 48 h; Jurkat cells for uptake imaging. - Transfection: 5 × 10⁵ activated T cells; 1.5 µg CAR-transposon + 0.5 µg transposase (total 2 µg) at N/P 40; 4 h incubation; IL-2 supplementation. - Expansion: EGFRvIII antigen/anti-CD28-coated plates. - Controls: Non-transfected cells; transposon-only transfection; EGFRvIII-negative U87 target cells. - No tumor challenge or in vivo efficacy model.
Key methods: Nanoparticle characterization: AFM, DLS/Zetasizer, zeta potential. - DNA binding/release: Agarose gel retardation, restriction digestion, DTT-triggered release. - Transfection: Flow cytometry for RFP/CAR expression; fluorescence microscopy. - Viability: CCK-8 assay. - Phenotype: Flow cytometry for CD4, CD8, CD62L, CCR7, CD45RO, CD45RA. - Function: LDH cytotoxicity assay against EGFRvIII-positive U87 cells.
Key results: Nanomicelle properties: Blank micelles ~62.7 nm; polyplex at N/P 40 ~134.5 nm and +20.9 mV; complete DNA condensation at N/P 20; DTT released DNA. - Transfection at N/P 40: 24.5% ± 3.3% positive cells; viability 82.3% ± 2.5% vs 97.5% ± 2.2% control. - Optimal conditions: 48 h activation, 5 × 10⁵ cells, 2 µg total plasmid, X-VIVO medium. - Stable CAR expression: Co-transfection with transposase gave 30.2% on day 2 and increased to 55.2% at end of culture; transposon-only dropped to 2.7%. - Phenotype: Less-differentiated T_N/T_SCM/T_CM = 56.2% ± 2.3%; CD3⁺CD8⁺ = 66.4% ± 7.1%. - Cytotoxicity: Average 17% killing at 20:1 E:T ratio against EGFRvIII-positive U87; no evident killing of EGFRvIII-negative U87.
Interpretation: The authors claim that polymeric nanomicelles provide a flexible and safe method for gene delivery to T lymphocytes. Co-delivery of PiggyBac transposon and transposase enabled stable transgene expression and produced functional CAR-T cells with memory phenotype, supporting a low-cost, non-viral alternative for CAR-T manufacturing and screening.
Limitations: In vitro only: No in vivo efficacy, tumor challenge, or survival data. - Modest efficiency: Initial transfection ~30%; stable expression ~55% after enrichment. - No direct comparison with electroporation/nucleofection or viral vectors. - Single CAR target: Only EGFRvIII CAR tested. - Small sample size: n = 3 for most experiments. - No long-term safety, genotoxicity, or insertional mutagenesis data. - No in vivo persistence or memory T-cell functional data. - Citation details incomplete in supplied excerpt (full author list, DOI missing).
